Electric switch.



No. 797,271. PATENTBDAUG. 15, 1905.

G. SQ DUNN. ELECTRIC SWITCH.

APPLICATXOH FILED AUG. 25. 1903.

Fig a- S51 E glu K Witnesses: Inventor,

cum s, Gamm m. nmouwoulnmns. Winnetou. n. C`

UNITED STATES PATENT OFFIOE.

GANO S. DUNN, OF EAST ORANGE, NEW JERSEY, ASSIGNOR TO CROCKER- VHEELER COMPANY, OF AMPERE, NEW JERSEY, A CORPORATION OF NEW JERSEY.

ELECTRIC SWITCH.

Specification of Letters Patent.

Patented Aug. 15, 1905.A

To all whom, t may concern:

Be it known that I, GANO S. DUNN, a citi- Zen of the United States or" America, and a resident of East Orange, county of Essex, and State of New Jersey, have invented certain new and useful Improvements in Electric Switches, oi' which the following is a specification.

This invention relates to an electric switch for the control and speed regulation of electric motors, whereby such shifting oil the connections as involves a considerable change in the voltage-drop at the armature or in the strengthof the motor-iield, or in the two combined, are accompanied by the temporary insertion of resistance in the armature-circuit in order to protect the armature from an excessive surge of current when the new connections are made. The resistance is cut out of the circuit by an automatic time device, which acts independently of the speed with which the controller is operated and cuts out the resistance when a deiinite period of time has elapsed after the new connections have been established by the movement of the controller. This resistance is cut in by the movement of the controller through the instrumentality of cams which are operated with the controller and which lift one of the contact-iingers away from the controller, and thereby open a shunt around a resistance in the armature-circuit. The contact-finger is returned into contact by a spring, and the action of the spring is delayed by a dash-pot for the requisite time, which is my preferred automatic time device.

In the accompanying sheet ot' drawings, which forms a part of this specification, Figure 1 is a side view of a cylinder or drumcontroller which is provided with my invention. Fig. Q is a transverse section through the controller on the line II II of Fig. l. Fig. 3 is a section, on a larger scale, through the dash-pot on the line III III of Fig. 2. Fig. 4 is a diagram of the electrical connections between the controller and motor and a development of the cylinder, showing the contacts thereon.

The invention has been made with reference to its use with controllers operated on what is known as the "multiple-voltage system, and its application is illustrated with the system of motor control set forth in Letters Patent of the United States, No. 735,352,

dated August 4, 1903, granted on my application, and Letters Patent of the United States, No. 736,537, dated August 13, 1903, granted on a joint application by Edwin R. Douglas and myself. The invention is illustrated in connection with a controller substantially such as is shown and described in the latter patent, in which current at different potentials is maintained between four conductors a b c (Z, and the two armature-leads of a motor M can be connected through a controller to any two of the supply-conductors by contacts carried on the controller-cylinder j), which will be termed the movable part of the controller and which is manually operated by a handle q. The field of the motor is supplied from two of the conductors through a series of resistance-sections r r, and contacts are provided on the controller for bridging all or a portion of the sections to secure closer regulation of the motor to the desired speed. In the off position of the controller, which is the position illustrated, all of the contacts of the controller-cylinder are clear of the contact-fingers and the armature-circuit is open. In addition one of the contact-fingers g,which is mounted on a lever 7L, is held away from the line of the other fingers by one of a series of cam-points c' on the controller-cylinder which underlies a cam-roll j, which is connected with the lever and contact-inger g. The lever is connected with the piston oi' a dash-pot l. The dash-pot is provided with an inlet ball-valve m, which is closed against an egress of air from the dash-pot by a ball which is held against the outlet by alight spring. This valve readily opens to admit air to the dash-pot when the piston rises. A second valve n permits the slow egress of air from the dash-pot. This valve has a small opening from the dash-pot under the end ot a screw and thence along a notch in the side of the screw. The screw is used to adjust the ow oi' air through the valve andregulate the time necessary Jfor the piston to fall and the linger to be returned into contact by the action of the spring s on the lever after a campoint has passed under and lifted the camroll. The shunt field-circuit is closed in all positions of the controller, thereby avoiding sparking, which would accompany the breaking of the circuit through the held-coils, and insuring a field to oppose and prevent an eX- cessive surge of current through the armature at the moment of closure of the armature-circuit in event of the controller being suddenly brought to an operative position, since a field cannot be established as quickly as an armature-circuit can be closed. In the oi position all of the sections of resista-nce fr are included in the field-circuit, and this circuit is from conductor c throug'h the sections of resistance, through lead f, the field of the motor, and the other lead f to the conductor The insertion of the resistance cuts down the field, so that the waste of current during the temporary stoppages of' the machine in the ordinary use of the controller will not be a serious matter. When the controller is moved from the off position to the first controller position, the contacts on the line 1 1 are brought under the contact-fingers and the cam-point is moved from under the cam-roll. An armature-circuit is then established from the conductor a through 'the contact-finger, the lower contact L", through one of the contacts t' on the same ring, through the contactfinger and armature-lead A, attached thereto, through the armature of' the motor, through the other armature-lead AA, through the resistance R and contact-finger to one of the controller-contacts 7o on the ring with the upper contact 7c', through this contact to contact-finger to conductor At the same time the field -resistance sections fr are bridged by the contacts on the ring r and the iield is brought to its full strength. The armaturecurrent is held in check by the resistance R in the armature-circuit until the field has built up and the armature has assumed its proper speed, so that sufficient counter electromotive force will be generated to oppose the excessive surge of' current through the armature. 'lhis change in field strength and armature speed requires a substantially definite time-usually from one to three seconds-and the dash-pot is adjusted so as to hold the finger g out of contact with the contacts on the ring' g for this length of time. Then this time has elapsed, the contact-finger g contacts with the underlying contact on the ring g and the resistance R is bridged. The armature-circuit is then from the lead AA to the contactfinger connected therewith, through contacts on the ring g', the contact-finger g, through the fiexible connection e, to the contact 7:, and contact 7U/ to conductor L. In passing' from the controller position, in which the contacts on the line 7 7 are under the contact-fingers, to the next controller position, in which the contacts on the line 10 10 are under the contact-fingers, thel armature connections at the first position with the conductors a and b, between which. a potential di'erence of, say, forty volts is maintained, are simultaneously broken at each of' the controller-contacts at which contact was made at the first position, and in the new position connections are made between the armature of the leads and the conductors c and cl, between which a potential difference of, say, eighty volts is maintained. At the same time a cam-point on the controller is brought under the cam-roll attached to the contact-finger g and removed by the mechanical operation of the controller. The resistance R is thereby cut into the armature-circuit. At the same time the mechanical operation of' the controller efi'ects the bridging of the resistances which were in the field-circuit in order that the field may be increased and the motor thereby protected against an excessive surge of' current to the armature due to the higher potential. Owing to the inductance ofl the field-coils and the sluggishness with which the magnetization of the field takes place, the resistance in the armature-circuit is necessary to prevent the increased potential which is applied to the armature-leads from immediately rising at the terminals of the armature, and the dash-pot acts as an automatic time device to hold the resistance in the armature-circuit for thc length of' time requisite for the building' up of the field. Likewise in passing' from controller positions 14 to 15, 18 to 19, 21 to Q2, and 23 to 24 there is a similar increase in the potential thrown on the armaturecircuit, which is accompanied by a change in the field strength, a cutting' in of' the armature resistance by the mechanical operation of' the controller, and its automatic cutting out by the automatic time device, consisting' of the dashpot and connections, after the requisite time has elapsed.

That Iclaim as new, and desire to secure by Letters Patent of' the United States. is-H 1. In a switch for dynamo-electric machinery, the combination of'acontact-fing'er, acontact-carrying movable part and contacts carried thereby, means for operating' the movable part to move the contacts in front of the finger, means for lifting the finger from the path of' the contacts, and means operating independently ofthe movement of' the movable part for returning the finger into the path of' the contacts, substantially as described.

2. In a switch fordynamo-electric machinery, the combination of' a contact-finger, a contact-carrying movable part and contacts carried thereby, means for operating the movable part to move the contacts in front of the finger, means operating' with the movable part for lifting the finger from the path of' the contacts, and means operating independently of' the movement of the movable part for returning the finger into the path ofl the contacts, substantially as described.

3. In a switch for dynamo-electric machinery, the combination of a contact-finger, a contact-carrying movable part and contacts carried thereby, means for operating the movable part to move the contacts in front ofl the finger, means for lifting the finger from the path of the contacts, and an automatic time device for returning the finger into the path of the contacts, substantially as described.

1. In a switch for dynamo-electric machinery, the combination of a contact-fing'er, a contact-carrying movable part and contacts carried thereby, means for operating the movable part to move the contacts in front of the finger, means operating with the movable part for lifting the finger from the path of the contacts, and an automatic time device for returning the finger into the path of the contacts, substantially as described.

5. In a switch for dynamo-electric machinery, the combination with a motor, a circuit therefor, and resistance in the circuit, ofnieans for effecting changes in the potential on the leads of the armature-circuit of the motor, means for cutting the resistance into said circuit, and an automatic time device for cutting the resistance out of said circuit, substantially as described.

6. In a switch for dynamo-electric machinery, the combination with a motor, field ,and armature circuits therefor, of means for effecting an increase in potential of the armaturecircuit, means for effecting an increase in the field strength, and an automatic time device for delaying the increase in potential at the armature-terminals, substantially as described.

7 .In a switch for dynamo-electric machinery, the combination with a motor, field and armature circuits therefor, and resistance in the armature-circuit, of means for effecting an increase in the potential on the leads of the armature-circuit, means for cutting the resistance into said circuit, means for effecting' an increase in the field strength, and an automatic time device for cutting the resistance out of said armature-circuit, substantially as described.

8. In a switch for dynamo-electric machinery, thc combination with a motor, a circuit therefor, and resistance in the circuit, of means for effecting changes in the potential on the leads of the armature-circuit of the motor, means for cutting the resistance into said circuit, automatic means for cutting the resistance out of said circuit, and a dash-pot for delaying' the action of said automatic means, substantially as described.

9. In a switch for dynamo-electric machinery, the combination with a motor, field and armature circuits therefor, of means for effecting an increase in potential of the armaturecircuit, means for effecting an increase in the field strength, automatic means for delaying the increase in potential at the armature-tei'- minals, and a dash-pot for controlling the action of said automatic means, substantially as described.

10. In a switch for dynamo-electric machinery, the combination With a motor, field and armature circuits therefor, and resistance in the armature-circuit, of means for effecting' an increase in the potential on the leads of the armature-circuit, means for cutting the resistance into said circuit, means for effecting an increase in the field strength, automatic means for cutting' the resistance out of said armature-circuit, and a dash-pot for delaying the action of said automatic means,

substantially as described.

11. In aswitch for dynamo-electric machinery, the combination with a motor, a circuit therefor, and resistance in the circuit,of acontact-finger for cutting the resistance out of said circuit, a contact-carrying movable part for effecting changes in the potential on the leads of the armature-circuit of the motor, means for lifting' the finger for cutting the resistance into said circuit, and means operating independently of the movement of the movable part for returning the finger into the path of the contacts,substantially as described.

12. In a switch for dynamo-electric machinery, the combination with a motor, a circuit therefor, andresistancc in the circuit, of acontact-finger for cutting the resistance out of said circuit, a contact-carrying movable part for effecting changes in the potential on the leads of the armature-circuit of the motor, means for lifting the finger for cutting' the resistance into said circuit, automatic means for cutting' the resistance out of said circuit, and a dash-pot for delaying the action of said automatic means, substantially as described.

13. In a controller for supplying electrical energy at different voltages to a motor, thc combination with a rotatable drum and stationary contact-fingers, of' means for inserting in the circuit of the motor-armature a suitable resistance when changing the supplyvoltage comprising a pivoted contact-finger, resilient means tending' to hold said fing'er in engagement with said drum, means for raising said finger out of contact with the drum y and means for retarding the return movement ofl said finger' toward the drum, substantially as described.

14. The combination with multivoltage supply-circuits, a motor and a controller therefor, of' means for temporarily inserting a resistance in series with the motor-armature when a change in its circuits takes place comprising' a drum-ring and a finger which is normally in contact therewith but which is raised out of engagement when a chang'e in the motorarmature circuits is made and is permitted to return only after a predetermined period of' time, substantially as described.

15. rlfhe combination with an electric motor havinga shunt field-magnet winding, of a controller comprising' a resistance, stationary and movable contact members, a cam for separating two of said cooperating members in order to introduce the resistance into the motor-armature circuit, a spring for moving to its normal position, and a Huid-controlled retarding means for governing the action of said spring, substantially as described.

` Signed by me in New York city, borough of Manhattan, this 18th day of August, 1903.

GANO S. DUNN.

lVi'tnesses:

SAMUEL NV. BALoH, HERBERT NOBLE. 

